Manual to Auto Swap (aka Blasphemy)

Hi all,

My last thread was about putting an NP-242 behind an AX-15...that plan is on hold indefinitely.

I have a physically demanding job that takes its toll on my back, and the problem isn't getting any better. I'm also doubtful it'll improve even after I stop doing this for a living (I fly for the military) based on x-rays and conversations with my docs. Nothing unbearable or worth complaining about, but driving a manual -- specifically one with a reasonably heavy clutch -- is getting old (just like me). My Jeep is my DD as well.

It pains me to consider this, because I searched for a manual XJ for so long. And I have enough love for my current Jeep (and mods/$$$ in it) that I don't want to just buy an auto XJ and move on. So, with that in mind, I'm considering doing an AX-15 to AW-4 swap (and bolting up the NP242 I have in the process).

Has anyone done this? Nearly all the writeups I see are the other way around. I'm considering just getting a donor 98+ XJ and making it factory. Looks like an RADesigns shifter is an option if I wanted to stop short of some wiring work, but I don't mind taking the time to make it 100% (might do the RADesigns shifter at a later time though if it seems worthwhile).

Outside of the donor Jeep, I plan on tracking down some 4.10 axles as well (I run 31x10.5 tires on a 3.5" lift).

On a final note, while I consider this...anyone out there with a good AW4 wanting to swap the other way around? Would need 98+ for all the wiring, electrical outputs/inputs to the trans, etc. I'm located in Virginia (Newport News area). Alternatively, any tips on finding a wrecked XJ? Would be nice to find one I need for <$1000.

If you're looking to find a wrecked donor, an auction site like copart.com would be a good place to look. I bet you could find an auto 4x4 XJ for pretty cheap there, I commonly see stuff like that on there for a few hundred bucks. I think they can arrange transport too if there isn't a yard nearby that has what you want.

Thank you for the reply.

What's everyone's thought on splicing in required AW4 connectors into my harness vs swapping the harness entirely? Both sound difficult, wondering what the path of least resistance is.

Replacement harness.

I removed and rewired my entire car and after that I am pleased with my simplification result for off-roading but it would definitely be easier to swap over a premade factory harness than rework or add wires.

Sounds like a good idea -- thanks for the input gents.

This is probably trending toward deserving its own thread, but I'll attempt to not shotgun-blast my questions all over the boards...what do folks look for when picking up salvage yard axles? I'm going to go with 4.10s prior to the swap (both as a last-ditch effort to try to save my manual by having to feather/slip the clutch less in traffic, and to prep for the auto swap if I do it) but will likely have to drive a few hours to pick the front and rear up. Any tips on getting a "good" one vs something that's already trashed?

I went manual -> auto in my 89 when the pilot bearing seized, took out the input bearing, and I had an AW4 sitting in the garage already. It wasn't as bad as you might think, but still a lot of time and effort.



You really need access to a donor to get all the small pieces like the console, etc. I think I made 3-4 trips to the local pull-n-save. Not sure about a 98, but on the 89 the wiring was mostly in it's own harness between the trans computer under the dash and the transmission with only a handful of wires going elsewhere. Constant and switched power, ground, tps signal (the 98 gets tee'd off the existing sensor versus have a separate output), brake pedal sensor, reverse light from the NSS, and probably something else I'm forgetting. Drive shaft lengths will change as the AW4 is about 1" longer than the AX15. I needed the extra length in the back after the lift, but had to grab a longer front shaft.



That 98 was a changeover year on the AW4, in particular the output speed sensor, so you'll need the trans computer and wiring from the same year.

lawsoncl said:

That 98 was a changeover year on the AW4, in particular the output speed sensor, so you'll need the trans computer and wiring from the same year.

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To clarify, they just need to match not necessarily all from a 1998. Preferably from a 98+. The engine computer from the manual won't talk to the tcu, which isn't a big deal.

lawsoncl said:

To clarify, they just need to match not necessarily all from a 1998. Preferably from a 98+. The engine computer from the manual won't talk to the tcu, which isn't a big deal.

Click to expand...

Thank you for the reply!

I agree, a donor seems like the best way to go. I'm currently trying to navigate the options on copart to find a good one.

Another question on this -- is there any advantage to the 4 pulse/rev 98+ AW4s versus the 1 pulse/rev AW4s found on 97 and prior XJs? I'd be swapping the harness over anyway so all the wiring would be fine, just curious about the transmission and pulses/sec itself.

Thanks!

Prefontaine said:

Another question on this -- is there any advantage to the 4 pulse/rev 98+ AW4s versus the 1 pulse/rev AW4s found on 97 and prior XJs? I'd be swapping the harness over anyway so all the wiring would be fine, just curious about the transmission and pulses/sec itself.

Thanks!

Click to expand...

I don't see any real advantage or disadvantage. The old sensors were mechanical reed relays, and the new ones are magnetic sensors. In theory more reliable, but I've never one of the old style fail.